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Pacific Ocean facts
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THE major feature of the Pacific Ocean is its enormous size: Not only is it the largest ocean in the world, it is also the world's largest single physical feature. With an area of about 166 million sqkm, it is twice the size of the Atlantic Ocean and occupies nearly a third of the surface of the earth--more than the area of all the earth's land surfaces.
Its average depth is the greatest of any ocean, and it also contains the deepest oceanic trenches. The deepest, the Mariana Trench (马里亚纳海沟), with a depth of about 11,000 metres, has a greater vertical dimension than the world's highest mountain--Mount Everest (珠穆朗玛峰), at 8,848 metres.
Around the boundaries of the Pacific Plate are many active volcanoes and frequent earthquakes. The presence of numerous volcanoes has caused the circum-Pacific (环绕太平洋) rim (边缘) to be called the Ring of Fire. Most of the world's active volcanoes are in the ring. Many are in densely populated areas, as is Nevado del Ruiz in Colombia, which erupted in 1985 and took more than 20,000 lives.
Earthquakes are more common in the Ring of Fire than are volcanic eruptions, and they have caused much damage, often made worse by unsuitable building methods and materials. In Central America and Mexico, for example, many houses are built of adobe, or sundried bricks. Walls of this material do not withstand the lateral motions of a quake well. Because populations are increasing rapidly in many parts of the Ring of Fire, including the United States, increasing damage from quakes and eruptions can be expected.
In 1972 a quake destroyed or badly damaged 75 per cent of the buildings in Managua, Nicaragua (尼加拉瓜). More than 11,000 people died, and more than 300,000 were left homeless.
(Part I)
(SD-Agencies)
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